The invention relates to an endoscope.
Without limiting its general application, the endoscope according to the invention is particularly suitable for tracheotomy. An endoscope used for this purpose is also referred to as a tracheoscope or bronchoscope.
In a tracheotomy procedure, when a patient whose normal breathing through the nose and mouth is impaired or no longer possible, an artificial route of respiration is established through the throat below the larynx. To do this, a trocar is used to create, from the outside, an incision through the throat and into the trachea, into which a tracheotomy cannula is later inserted through which the patient then breathes or can be ventilated.
A difficulty that arises in an operation of this kind lies in determining the exact position of the incision for the subsequent tracheotomy cannula. For this purpose, as has been described in document DE 695 27 958 T2; an endoscope is introduced through the patient's mouth and into the trachea, where the distal end of the shaft of the endoscope comes to lie just below the larynx. Arranged in the known endoscope there is a light guide whose distal end, from a distal opening of the endoscope shaft, radiates light in the direction of the anterior wall of the trachea. A spot of light is then visible on the skin of the front area of the throat, and the illuminated area of the trachea is also made visible. By moving the endoscope or light guide, the light spot can now be positioned in such a way that it comes to lie between two cricoid cartilages or tracheal rings of the trachea. The cricoid cartilages or tracheal rings stand out from the rest of the tracheal wall by virtue of a different intensity or coloration of the light spot. As soon as the light spot is correctly positioned, the aforementioned incision through the skin and into the trachea can now be made by means of a trocar with the aid of the light spot.
The known endoscope has a light guide which is continuously straight and whose light-emitting window is cut obliquely in relation to the longitudinal axis of the light guide. This results in an obtuse angle of radiation of the light relative to the longitudinal axis of the light guide. Since the light is not radiated strictly to form a point but instead in an areal manner, the oblique incidence of light on the tracheal wall has the effect that the visible light spot is “smudged”. To ensure a perpendicular incidence of the beam of light on the tracheal wall, the known endoscope has to be held obliquely relative to the longitudinal axis of the trachea, but the confined spaces in the region of the larynx and mouth through which the endoscope is introduced means this is not possible. If the light spot visible from outside is smudged, however, the incision into the trachea for the subsequently inserted tracheotomy cannula cannot be made with pinpoint precision. If this incision is not formed with pinpoint precision, the result of the tracheotomy may be compromised.